I'm thinking that having experience with a capability based operating system such as Fuchsia or Genode as a daily driver will be quite valuable, as you'll be ahead of the adoption curve. I hope to have this happen myself next year.
If you haven't already, I recommend doing the Advent of Code puzzles, all of them, in whatever language you are comfortable in. Redo them in whatever language you want to learn, ad infinitum. I personally haven't gotten through all them in Pascal yet. I did last year in real time, and except for day 19, and current in 2021.
I suggest you learn a little bit of practical machining, that done in machine shops. The process of using machine tools to make things, otherwise known as subtractive manufacturing. I'd also suggest you learn additive manufacturing as well. It is good to understand how the atoms around you came to be configured as they are.
There you go, 3 things to learn for 2022.